**NAME**

Heatexchange_computeDt

**SYNOPSIS**

Heatexchange_computeDt(integer(IN) :: blockID, ) integer(IN) :: blkLimits(2,MDIM) integer(IN) :: blkLimitsGC(2,MDIM) real,pointer:: solnData(:,:,:,:), real(OUT) :: dt_heatXchg, real(OUT) :: dt_minloc(5))

**DESCRIPTION**

compute a burning timestep limiter, by trying to force the energy generation from burning to be smaller than the internal energy in a zone. The timestep limiter would be: eintN dt = hx_dtFactor * ------ burn qNdot qNdot is energy/mass/s, so the time factor is already in there, and we are doing eintN dt = hx_dtFactor * ------ * dt burn qNdot*dt qNdot*dt is the amount of energy / mass deposited in a zone by burning. eintN is the internal energy / mass in that zone. If qNdot*dt is 2x eintN, then we want a timestep that is half the size. hx_dtFactor is a prefactor to scaling the timestep. In general, we aim for qNdot*dt < hx_dtFactor * eintN. For good coupling between the hydro and the burner, hx_dtFactor should be < 1.

**ARGUMENTS**

blockID -- local block ID blkLimits -- the indices for the interior endpoints of the block blkLimitsGC -- the indices for endpoints including the guardcells solnData -- the physical, solution data from grid dt_heatXchg -- variable to hold timestep constraint dt_minloc(5) -- array to hold limiting zone info: zone indices (i,j,k), block ID, PE number

**PARAMETERS**

hx_dtFactor A parameter, such that qNdot*dt < hx_dtFactor * eint, that is, the energy release from burning divided by the internal energy in that zone is < hx_dtFactor.

**SEE ALSO**

Driver_computeDt

High-Energy Density Physics

Thermonuclear-Powered Supernovae

Fluid-Structure Interaction

Implicit Solvers

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The Flash Center for Computational Science is based at the University of Chicago and is supported by U.S. DOE and NSF.